2 files changed, 84 insertions, 5 deletions

diff --git a/drivers/gpu/drm/i915/i915_gem_dmabuf.c b/drivers/gpu/drm/i915/i915_gem_dmabuf.c
index 3a00ab3ad06e..c60a8d5bbad0 100644
--- a/drivers/gpu/drm/i915/i915_gem_dmabuf.c
+++ b/drivers/gpu/drm/i915/i915_gem_dmabuf.c
@@ -23,9 +23,13 @@
  * Authors:
  *      Dave Airlie <airlied@redhat.com>
  */
+
+#include <linux/dma-buf.h>
+#include <linux/reservation.h>
+
 #include <drm/drmP.h>
+
 #include "i915_drv.h"
-#include <linux/dma-buf.h>
 
 static struct drm_i915_gem_object *dma_buf_to_obj(struct dma_buf *buf)
 {
@@ -218,25 +222,73 @@ static const struct dma_buf_ops i915_dmabuf_ops =  {
         .end_cpu_access = i915_gem_end_cpu_access,
 };
 
+static void export_fences(struct drm_i915_gem_object *obj,
+                          struct dma_buf *dma_buf)
+{
+        struct reservation_object *resv = dma_buf->resv;
+        struct drm_i915_gem_request *req;
+        unsigned long active;
+        int idx;
+
+        active = __I915_BO_ACTIVE(obj);
+        if (!active)
+                return;
+
+        /* Serialise with execbuf to prevent concurrent fence-loops */
+        mutex_lock(&obj->base.dev->struct_mutex);
+
+        /* Mark the object for future fences before racily adding old fences */
+        obj->base.dma_buf = dma_buf;
+
+        ww_mutex_lock(&resv->lock, NULL);
+
+        for_each_active(active, idx) {
+                req = i915_gem_active_get(&obj->last_read[idx],
+                                          &obj->base.dev->struct_mutex);
+                if (!req)
+                        continue;
+
+                if (reservation_object_reserve_shared(resv) == 0)
+                        reservation_object_add_shared_fence(resv, &req->fence);
+
+                i915_gem_request_put(req);
+        }
+
+        req = i915_gem_active_get(&obj->last_write,
+                                  &obj->base.dev->struct_mutex);
+        if (req) {
+                reservation_object_add_excl_fence(resv, &req->fence);
+                i915_gem_request_put(req);
+        }
+
+        ww_mutex_unlock(&resv->lock);
+        mutex_unlock(&obj->base.dev->struct_mutex);
+}
+
 struct dma_buf *i915_gem_prime_export(struct drm_device *dev,
                                       struct drm_gem_object *gem_obj, int flags)
 {
         struct drm_i915_gem_object *obj = to_intel_bo(gem_obj);
         DEFINE_DMA_BUF_EXPORT_INFO(exp_info);
+        struct dma_buf *dma_buf;
 
         exp_info.ops = &i915_dmabuf_ops;
         exp_info.size = gem_obj->size;
         exp_info.flags = flags;
         exp_info.priv = gem_obj;
 
-
         if (obj->ops->dmabuf_export) {
                 int ret = obj->ops->dmabuf_export(obj);
                 if (ret)
                         return ERR_PTR(ret);
         }
 
-        return dma_buf_export(&exp_info);
+        dma_buf = dma_buf_export(&exp_info);
+        if (IS_ERR(dma_buf))
+                return dma_buf;
+
+        export_fences(obj, dma_buf);
+        return dma_buf;
 }
 
 static int i915_gem_object_get_pages_dmabuf(struct drm_i915_gem_object *obj)
diff --git a/drivers/gpu/drm/i915/i915_gem_execbuffer.c b/drivers/gpu/drm/i915/i915_gem_execbuffer.c
index a1da3028a949..71834741bd87 100644
--- a/drivers/gpu/drm/i915/i915_gem_execbuffer.c
+++ b/drivers/gpu/drm/i915/i915_gem_execbuffer.c
@@ -26,14 +26,18 @@
  *
  */
 
+#include <linux/dma_remapping.h>
+#include <linux/reservation.h>
+#include <linux/uaccess.h>
+
 #include <drm/drmP.h>
 #include <drm/i915_drm.h>
+
 #include "i915_drv.h"
+#include "i915_gem_dmabuf.h"
 #include "i915_trace.h"
 #include "intel_drv.h"
 #include "intel_frontbuffer.h"
-#include <linux/dma_remapping.h>
-#include <linux/uaccess.h>
 
 #define  __EXEC_OBJECT_HAS_PIN          (1<<31)
 #define  __EXEC_OBJECT_HAS_FENCE        (1<<30)
@@ -1205,6 +1209,28 @@ void i915_vma_move_to_active(struct i915_vma *vma,
         list_move_tail(&vma->vm_link, &vma->vm->active_list);
 }
 
+static void eb_export_fence(struct drm_i915_gem_object *obj,
+                            struct drm_i915_gem_request *req,
+                            unsigned int flags)
+{
+        struct reservation_object *resv;
+
+        resv = i915_gem_object_get_dmabuf_resv(obj);
+        if (!resv)
+                return;
+
+        /* Ignore errors from failing to allocate the new fence, we can't
+         * handle an error right now. Worst case should be missed
+         * synchronisation leading to rendering corruption.
+         */
+        ww_mutex_lock(&resv->lock, NULL);
+        if (flags & EXEC_OBJECT_WRITE)
+                reservation_object_add_excl_fence(resv, &req->fence);
+        else if (reservation_object_reserve_shared(resv) == 0)
+                reservation_object_add_shared_fence(resv, &req->fence);
+        ww_mutex_unlock(&resv->lock);
+}
+
 static void
 i915_gem_execbuffer_move_to_active(struct list_head *vmas,
                                    struct drm_i915_gem_request *req)
@@ -1224,6 +1250,7 @@ i915_gem_execbuffer_move_to_active(struct list_head *vmas,
                 obj->base.read_domains = obj->base.pending_read_domains;
 
                 i915_vma_move_to_active(vma, req, vma->exec_entry->flags);
+                eb_export_fence(obj, req, vma->exec_entry->flags);
                 trace_i915_gem_object_change_domain(obj, old_read, old_write);
         }
 }